1. Field of the Invention
The present invention relates to a magnetic recording medium fabrication method.
2. Description of the Related Art
Recently, a magnetic storage apparatus may be provided in various products, including a personal computer, a video recorder, a data server, and the like, and the importance of the magnetic storage apparatus is increasing. The magnetic storage apparatus includes a magnetic recording medium that magnetically stores electronic data by magnetic recording. Examples of the magnetic storage apparatus include a magnetic disk drive, a flexible disk drive, a magnetic tape apparatus, and the like. A HDD (Hard Disk Drive) is an example of the magnetic disk drive.
For example, a general magnetic recording medium has a multi-layer stacked structure including an underlayer, an intermediate layer, a magnetic recording layer, and a protection layer that are deposited in this sequence on a nonmagnetic substrate, and a lubricant layer coated on a surface of the protection layer. In order to prevent mixing of impurities between the layers forming the magnetic recording medium during fabrication of the magnetic recording medium, an in-line vacuum deposition apparatus is used to continuously stack the layers under decompression, as described in Japanese Laid-Open Patent Publication No. 8-274142, for example.
In the in-line vacuum deposition apparatus, a plurality of deposition chambers having a deposition means capable of depositing a layer on the substrate are connected via a gate valve, together with a chamber for carrying out a thermal process and an auxiliary chamber, are provided in order to form a single deposition line. When the substrate is set on a carrier and passes through the deposition line, the layers are successively deposited on the substrate to fabricate the magnetic recording medium having the desired structure.
Generally, the deposition line is arranged in a ring shape, and a substrate loading and unloading chamber is provided in the deposition line in order to load and unload the substrate with respect to the carrier. The carrier, which passes through the deposition chambers of the deposition line, reaches the substrate loading and unloading chamber where the substrate having the layers deposited thereon is unloaded from the carrier. In addition, after removing the substrate from the carrier, new substrate to be subjected to the deposition is loaded onto the carrier in the substrate loading and unloading chamber.
In addition, as a method of forming the lubricant layer on the surface of the magnetic recording medium, a vapor-phase lubrication has been proposed in Japanese Laid-Open Patent Publication No. 2004-002971, for example. The vapor-phase lubrication places the magnetic recording medium within a vacuum chamber, and introduces gas lubricant into the vacuum chamber.
In addition, a magnetic recording medium having a lubricant layer formed by two layers has been proposed in Japanese Laid-Open Patent Publication No. 2006-147012, for example. The lubricant layer of this proposed magnetic recording medium is formed by a fixing layer (or bond layer) that is provided on the side of the protection layer, is chemically stable, and has a suitable bond with respect to the protection layer, and a fluid (or free layer) that is provided on the surface side of the magnetic recording medium and is mainly made of a material having a low coefficient of friction.
Furthermore, forming the protection layer from carbon nitride and forming the lubricant layer from perfluoropolyether that includes a terminal group having an amine structure, in order to increase the bonded ratio between the protection layer and the lubricant layer to 70% or higher, has been proposed in Japanese, Laid-Open Patent Publication No. 2000-222719, for example. The bonded ratio is measured by dipping the magnetic recording medium formed with the lubricant layer in a fluorocarbon solvent for five (5) minutes while applying ultrasonic waves, and measuring the absorbance in a vicinity of 1270 cm−1 at the same position on the same medium before and after the dipping using ESCA (Electron Spectroscopy for Chemical Analysis). The bonded ratio is defined as a percentage of the ratio of the absorbances before and after the dipping, using a formula [{(Absorbance After Dipping)/(Absorbance Before Dipping)}×100].
When the contact between the magnetic recording medium and the magnetic head is taken into consideration, the coefficient of friction of the lubricant layer is preferably low. On the other hand, when a corrosion resistance of the magnetic recording medium is taken into consideration, a coverage of the surface of the protection layer provided by the lubricant layer is preferably high.